I've seen people drive for hours with their turn signal on while driving the interstate. I have zero faith that an icon is going to get anyone's attention. The entire concept suffers from a basic UX flaw that computer programmers have known for a long time. When a user sees the same thing over and over, they begin to ignore it. Ever have one of those "Ok/Cancel" dialog boxes pop up on your computer and you immediately look for a way to dismiss it, without paying any attention to the contents? Users will do the same thing with this system.

The trouble with accident avoidance systems is that they need to kick in *only* when there is an impending accident. That is a very difficult problem. Also, the timing is absurdly difficult. Many of us already have accident avoidance systems. They're commonly obtained under the trade name: "wife". The problem with them is that they're always going off when you don't need them, so you really just wish they'd be quiet. If you could find a way to disable them, you would. I don't see how an electronic "wife" would be any better received.